Telegraph exchange system



M 2; 1938.1 F. s; KINKEAD 2,114,023

TELEGRAPH EXCHANGE SYSTEM Filed Aug. 30, 1955 2 Sheets-Sheet 1 Mi k;-

RECTI-HER 8V 9% M ATTORNEY April 1938. F. s. KINKEAD 2,114,023

/ I TELEGRAPH EXCHANGE SYSTEM Filed Aug. 30, 1935 2 Sheets-Sheet 2 I I IH lll H r FIG; 2

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$8 AP "-1 I 7 FIG 3A INVENTOR F? S; K/N/(EAD Br 9/ Z j ATTORNEY PatentedApr. 12, 1938 PATENT OFF-ice TELEGRAPH EXCHANGE SYSTEM Fullerton S.Kinkead, Ridgefield Park, N. J., assignor to Bell TelephoneLaboratories, Incorporated, New York, N. Y., a corporation of New YorkApplication August 30, 1935, Serial No. 38,503

9 Claims.

The present invention relates to line and subscriber circuits forteletypewriter switching systems of the type adapted to give service tosubscribers.

An object of the invention is to provide subscriber station and linecircuit equipment by means of which subscribers may be given unattendedservice, i. e., the subscribers station may be rendered operative fromthe central ofiice for the reception of a message and after thetermination of the message, the apparatus may be restored to the normalidle condition suitable for the reception of another call or the makingof a call when the subscriber returns. A more particular object is toprovide equipment whereby unattended service may be given the subscriberthrough a central office equipped with certain types of apparatus now inuse.

A feature of the invention consists of equipment whereby upon connectionof a subscribers line through a central oflice to .a distant sub scriberupon a multi-party line, the supervisory operations normally performedby the subscribers operator upon the multi-party line to stop the motorat his station and produce a disconnect signal at the central office,will not leave rumiing the motor of the subscribers station which hasbeen connected to said multi-party line.

A general object is to improve the supervisory signal arrangements ofteletypewriter switching systems so that unattended service may be givenand the necessary supervisory signals produced at the central officewith greater celerity and eflicienc'y.

In a preferred embodiment of the invention, the line supervisoryequipment is so arranged that a recall or disconnect signal at thecentral ofiice will be produced at the termination of a communication orat such other time as desired upon the transmission of a special codecombination adapted to operate a pull bar contact followed by a seriesof five break signals with relatively short closed periods between thebreak signals. The subscribers station is provided with a special keyeither normally connected in or connectable in the line ,for the purposeof sending five break signals. The five break signals are not necessaryfor restoring the subscribers station to the idle condition but it is soarranged that upon the transmission of such break signals the circuit isrestored to the idle condition. The necessity for this arises from thefact that certain multi-station lines with which the line may beconnected for communication require a pullbar operating combinationsignal followed by five break signals for supervisory purposes.

It will be noted that the arrangements of Figs. 2, 3, 3A and 3B areessentially those of Figs. 4

5, 5A and 5B of Lane-Locke Patent 1,979,273, I

tended service for reception of messages over a i normally closedtelegraph line to a central office.

It may also transmit and receive when attended.

The motor M may be driven by a public utility power supply or othersuitable alternating current source S and it may be started by a breaksignal impulse of about one second duration, but not less than secondduration. may be stopped and the circuit restored to normal by anotherwise idle upper case code com bination as upper case H.

Circuit arrangements of the preferred embodiment are shown in theaccompanying drawings wherein,

Fig. 1 discloses, at the left of the figure, a subscribers stationequipment and at the righthand end the line terminating equipment at thecentral oilice;

Fig. 2 discloses the general organization of cord circuit equipment at acentral office at which the subscribers line terminates and by' which itmay be connected to other subscribers lines, and

Fig. 3 shows diagrammatically the operator's teletypewriter circuitconnectable to any cord circuit, Fig. 3A indicates a second operator'sequipment which may be provided, and Fig.'3B a maintaining circuit usedwhen Fig. 3A is not employed.

Assume that the subscribers circuit is idle. The line T, R is closed.Relays A, B and C are released. Relay D is operated by current flowingfrom the rectifier REC over back contacts of certain armatures of relaysA, B and C in series. The receiving magnet iii of the teletypewriterwill be energized over a path from negative REC through its winding andthence to ground over the contact of receiving relay RR and also overthe inner upper back contact of relay C and the make contact of relay D.Opening of right-hand.

The motor contact I of the receiving relay RR will not release magnet l6so long as relay Dis operated. However, when the contact 2 of relay RRis closed, the winding of relay D will be short-circuited, but relay Dis a slow-release relay and it will not release during short lineinterruptions and consequently magnet [6 will not release.

Subscriber calls To start the motor of his station the operator willopen break key 36 (corresponding to break key I36 of Morton et al.Patent 1,931,672, October 24, 1933) for one second. This will operaterelay RR to contact 2 for a time sufficient to allow relay D to release.When key I36 is closed, the line will be closed again and cause contacts86 and 8'! (similarly identified in Patent 1,931,672) to close thecircuit of the teletypewriter motor M and to winding of relay A throughrectifier R. The rectifier R conducts in one direction only and thusshort-circuits the winding of relay A during each one-half cycle ofsixty cycle alternating current. Relay A does not operate on sixty cyclealternating current but operates without chattering on the pulsatingcurrent. Upon operating, relay A closes the winding of relay B and opensthe operating path of relay D. The relay B, upon operating, opens theshort-circuiting path and the operating path of relay D and prepares itsown locking path. When relay D releases a locking path will be closedfor relay B from negative rectifier REC, winding of relay B, upper makecontact of relay B and back contact of relay D. Relays A and B are nowoperated and relays C and D released.

At the central oflice, slow-release relay E will release when relay Lreleases and apply ground over the normally closed contacts of selectorSEL to the winding of slow-release relay F. When relay F operates, apath is prepared for operation of the selector rotor magnet ROT. Whenthe line is closed, relay L will reoperate and close the operating pathof relay E. The winding of relay F is then short-circuited. It does notrelease immediately and before releasing, a circuit will be closed overthe left-hand contact 'of relay E and make contact of relay F to rotormagnet ROT. The wipers of the selector SEL will ad- Vance one step andclose the off-normal contacts ON of the selector. Closure of lead I08establishes a circuit for relay 3 which looks up and lights lamp 4 andenergizes relay 1 which may be the usual night alarm relay. W'hen relayF releases, the connection of the upper off-normal contact will close apath through the release magnet RLS to the normal make on releasecontact of relay F and the make contact of the energized relay E. Thiscauses the selector to release.

The central ofiice operator answers the call by placing plug AP in jackLJ to deenergize lamp 4 and then connecting the calling subscriber to acalled subscriber by means of the cord circuit of Fig. 2.

Operator calls a subscriber Now let us examine the operation when thecentral ofiice operator calls a subscriber after placing the callingplug CP in the line jack LJ. By means of the operators break key 264,the line circuit is interrupted for one second or more. Under thiscondition, the operators break key causes the actuation of relay 2&8,causing it to move its armature from plus battery to negative battery.When the armature is thus moved, the line circuit begins at negativebattery in the repeater, passes over coil 228, resistance 2H3, uppermake contact of relay 215, tip of plug 01?, tip of jack LJ, relay L,line conductor T, relay RR, teletypewriter contacts, and conductor R tonegative battery. The circuit is thus terminated at each end in negativebattery and is effectively opened. The opening of the line causesexactly the same sequence of operations at the subscribers station aswhen the subscriber was assumed to open key I36. The central ofliceoperator may now send bell signals (code combinations operating a bellpull-bar on the subscribers teletypewriter machine). If the subscriberis present, he may answer by typing one or more characters in reply; ifabsent, a message may be sent and recorded on his machine.

During communication of the central ofiice operator or of a distantstation with the subscriber, the relays A and B will remain operated,relays C and D released and the receiving magnet I6 will operate undercontrol of the receiving relay.

Cooperation with party line station In the application of Kinkead,Serial No. 13,859, filed March 30, 1935, is disclosed a teletypewriterexchange system in which a central ofiice operator may select a stationon a multi-party line for communication through an exchange with anotherparty on a single or a multi-party line. In said system, the operationof stopping all stations and clearing a call involves the sending to orfrom the central oflice or the sending to or from the party line stationa series of five break impulses. It was found that when a subscribersstation of the previously known unattended type was connected forcommunication (over one or more exchanges or through none or one or moretrunks) with a party line station of the specific type of saidKinkeadapplication or a slightly modified type adapted to connect toswitchboards with closed lines, an operating diificulty arose. Thisdiificulty comprised, in part, the fact that a disconnect signal fromthe party line station to his switchboard left the connected unattendedstations motor running. To prevent such an occurrence, among otherreasons, the present system described herein was evolved.

Disconnect operation The operation of the apparatus at the subscribersstation will be the same whether the disconnect signal originates in aconnected station or is sent by the subscriber himself. In either case,it will consist of a motor stopping code combination such as shift-shift(see Patent 1,931,672), followed by five spacing impulses. I1 thesubscriber of Fig. l disconnects, the five impulses are sent by a singlerotation of the rotary pulse sending key K. The operation at the stationshown or any similar connected station will be as follows: Upon theshift-shift code combination, the motor control contacts 86, 8'! willopen to stop the motor M and release the relay A. Upon releasing, theback contact of relay A will extend the direct current circuit from therectifier REC to the lower inner back contact of relay B and the windingof relay C. In operating, relay C will close a path through its upperouter make contact to hold the magnet it operated. Relay C will'preparea path to the winding of relay D as follows: Negative side of rectifierREC, winding of relay D, lower inner make contact of relay C to contact2. Relay C will also prepare its own locking path from negativerectifier REC, through winding of relay C and inner upper make contactto open armature contact of relay D.

Thus the relays B and C will remain operated and relays A and D releaseduntil the line is next openedv When the line is opened, the relay RRenergized during the five bre'akpulses.

will operate to contact 2 and relay D will operate. This will close thelocking path of relay C and open the locking path of relay B. Relay Bwill release and open the operating path of relay C which willremain'locked over the contacts of relay D. Since relay D is of theslow-release type, it will remain operated until the line is 7 closedand the relay RR operated to contact 1. Relay C remains operated andrelay D remains operated and consequently magnet l6 remains Relay D willremain operated since the closed periods of theline between five breakpulses will be of short duration. After the last pulse and the line isclosed, the relay D will finally release and open the locking circuit ofthe relay C. When relay C releases, the receiving relay armature will beon contact I owing to the previous closure of the line T, R and themagnet IE will not be released. It is necessary that the local ordistant station operator or the switchboard operator send at least onebreak signal pulse or a series of five break signals following the motorstop combination. Otherwise, the motor can not be started again by asingle break impulse.

If the local power source S used to operate the motor M fails, the motormay be started when the power comes on again. In such case the motor maybe stopped locally or from the central office by the usual procedure.

The central office line terminating equipment in the case of adisconnect signal from the subscriber operates as follows: Lamp 5, whichis a busy lamp will be lighted under control of operated relay 6; relay3 will be released and lamp 4 dark. When key K is operated to send fivebreak pulses, each subsequent short closure following thefirst fourpulses will step the selector SEL up one contact by the operation ofrelay E following each break. Following the fifth open r pulse, theselector SEL will step to the fifth contact, the lead N will be closedto ground to actuate relay 205 in the cord circuit which looks up. Theoperating path for relay 205 is from ground, brush arm of selector SEL,lead N, ring of jack LJ, ring of plug AP or CF, winding of relay 205,left make contact of relay 2M or make contact of relay 2 l5 to battery.The locking circuit of relay 205 by which it looks up' and holds lamp221 lighted is obvious as is the breaking of this locking circuit whenthe plugs AP and CP are pulled down from their associated jacks.

When the relay F releases after the fifth pulse, the selector will berestored to normal by the connection of the release magnet RLS to groundover the off-normal contacts and the contact of energized relay E.

During communication, the relay L will follow line pulses but theslow-release relay E will remain operated on all except break impulsesof greater than character pulse length, When the line is closed after abreak signal pulse, the selector will be advanced one step but willcause no harmful result because relay 6 is actuated and the selectorwill release each time the line is closed.

It will be seen that a system in accordance with the present inventionis well adapted to work with systems in which a station requires five(or some other predetermined number) pulses to effect a disconnectoperation and that two or more local stations of the present type maywork with each other, or with systems requiring five disconnect pulses,or with systems in which 'disconnect is accomplished by a shift-shiftmotor stop combination followed by a single break signal pulse. Anadvantageous featureof the system is that short line interruptions willnot resuit in starting the motor of the subscriber station.

What is claimed is:

1. A subscriber station arrangement for printing telegraphcommunication-systems comprising a relay arrangement whereby the motorof the subscriber station may be set into operation by a break signal,in combination with a pull-bar contact for stopping the motor, and meansincluding a combination of relays including a slow-release relay andfast operating relays whereby a plurality of break signals with shortintervening line closures of the line after the operation of thepull-bar contact leaves the motor of the subscriber station in stopcondition, said slow-acting relay being connected to prevent one of saidfast operating relays from assuming motor starting position.

2. A printing telegraph station comprising a line connected to ateletypewriter machine having a motor, means for stopping said motorcomprising elements responsive to a chosen code combination, a magnetassociated with said machine actuatable to a position to restart saidmotor upon the first operation of said magnet to said position afterreception of said code combination, and means comprising a combinationof relays including a slow-release relay operable under the control ofany indefinite plurality of break signal pulses with short interveningclosures of said line following the receipt of said combination toprevent operation of said relay to motor starting position as a resultof transmission over said line of said plurality of break signal pulses.

3. A subscriber station for teletypewriter communication throughexchanges provided with a relay arrangement controlling contacts forstarting the motor upon reception. of a break signal of more than adefinite duration, and a pull-bar contact for stopping the motor uponreception of a definite code combination characterized by the inclusionof instrumentalities comprising relay equipment including fast andslowacting relays controlling the relay arrangement for starting themotor whereby a plurality of line interruptions with short interveningline closures following the transmission or reception of the specialcode combination leaves the subscriber station in normal idle conditionwith the motor thereof stopped.

4. A teletypewriter communication system comprising a central office forinterconnecting lines, lines to be interconnected, a teletypewriter ofthe Baudot code type including a driving motor operatively connected toeach line for communication thereover, automatic motor start and stopmechanism connected to the teletypewriter of one of said lines forstarting said motor from said central office on open and closure of saidline and stopping said motor by a code combination, and means includinga slow operating device connected to the teletypewriter of said line forpreventing the starting of said motor upon the receipt, with the motorstopped, of a series of line interruptions separated by less than apredetermined time.

5. A system according to claim. 4 wherein said means includes a relayfor placing said motor in condition to be started upon line closure of apredetermined time following said line interruption.

6. In a system in accordance with claim 4, a device at the outlyingterminus of said line for sending a predetermined number of lineinterruptions independently of said teletypewriter and regardless ofwhether the motor thereof be operating or idle.

7. A system according to claim 4 including a device at the outlyingterminus of said line for sending a predetermined number of lineinterruptions, a link circuit and a disconnect signal device at saidcentral ofiice, and means operative when said link circuit is connectedto said line to operate said signal device in response to said series ofline interruptions.

8. A station for printing telegraph communication comprising a receivingrelay and a teletypewriter control magnet, an energizing path for saidmagnet operatively opened and closed under control of said relay and aseparate energizing path for said magnet closed by an operatedslowrelease device and an unoperated relay.

9. A station for printing telegraph communication comprising a receivingrelay and a teletypewriter control magnet, an energizing path for saidmagnet operatively opened and closed under control of said relay, aseparate energizing path closed by a relay when operated, and a thirdenergizing path closed by said relay when unoperated provided anotherrelay is operated, said other relay being slow-release and controlled bysaid first-named relay.

FULLERTON S. KINKEAD.

